Which kind of verb should it be used after the phrase "each item" in the following sentence?

The law requires that each item clearly display the warranty information.

Should it be "displays" or "display" is correct?

Edit. Just to clear this up a little bit, let me explain that I got the sentence from a TOEIC book and that it called my attention on whether is correct or not.

Also

This question is diferent from others because I'm asking specifically about this sentence and phrase. Furthermore, I asked my teacher about it and she told me that it might be correct because they can be refering the word "item" as a whole, so if that is the case plural verb should be correct but using the word item as a singular thing it should be singular verb, but only they know what they tried to convey by saying "each item."

The other duplicate is “Require that every lightbulb have/has” not 'Each' with plural or singular verb', which does not cover the usage here. // The actual answer is that both 'display' (what was traditionally called the 'mandative subjunctive' mood, which has the same form as the infinitive) and 'displays' ([third person singular] indicative) are grammatical here. As is the periphrastic should construction: 'The law requires that each item should clearly display the warranty information.'
– Edwin AshworthApr 2 '16 at 7:37

2 Answers
2

This is a great question, and interestingly enough it isn't a matter of the "each item..." rule as you suggested:

Normally, when you have a sentence where the subject is "each" of some group, the verb is singular. For example:
Each member of the track team runs fast.

However, when you add "requires that" into the sentence, a different rule takes precedence: the verb must be put into the subjunctive. For example:
The school requires that each student pass P.E. to graduate.

Normally, since "student" is singular, it would be "passes," but the subjunctive singular form of "to pass" is "pass."

In your example, "each" is singular - so the verb form must be singular - but the verb should also be subjunctive because of the "requires that." Hence, you use the singular subjunctive form of "to display," which is "display" (coincidentally the same as the plural indicative form of "to display," which is why it might seem like they incorrectly used the plural and violated the "each" rule).

Nick, I think your answer solved all regarding this matter it clearly states why plural verb should be used your answer is the best, you won the contest. Thank you so much!
– Manuel HernandezApr 1 '16 at 19:04

'[T]he verb must be put into the subjunctive' is not true. It may be put into what was known in traditional grammar as the [mandative] subjunctive, but as CGEL points out, the indicative mood is also acceptable. The Leech reference above explains the true situation in more detail; of the three options available, the periphrastic should construction seems the most frequently used according to one survey at least.
– Edwin AshworthApr 2 '16 at 7:49

According to Michael Swan's Practical English Usage, "each" is a determiner used before a noun and it needs a singular verb. Only "each of" -followed by a pronoun or determiner- is sometimes used with a plural verb. However this is only considered correct in an informal style.

Each new day is different. Each of them has problems. Each of them
have problems. (more informal)

I suppose the latter is due to "proximity" agreement. When we don't think twice and use
"have" because "them" is plural.